1. Field of the Invention
Chemical mechanical polishing (CMP) apparatus are known as apparatus for high precision polishing operations to be conducted on SOI substrates, semiconductor wafers made of Si, GeAs and/or InP, wafers carrying an insulation film or a metal film on the surface and produced in the process of forming semiconductor integrated circuits and substrates to be used for displays in order to meet the demand for extra-miniaturization and multi-level arrangement of semiconductor devices in recent years.
2. Related Background Art
Firstly, a known CMP apparatus will be described by referring to FIG. 21 of the accompanying drawings. FIG. 21 schematically illustrates a known CMP apparatus. Referring to FIG. 21, an object of polish (wafer) 100 is held by an object-of-polish-holding means 300 with the surface to be polished facing downward and polished by means of a polishing pad 200 typically made of polyurethane and having a caliber greater than the diameter of the object of polish 100. The polishing pad 200 normally has undulations on the surface or is porous. The object of polish 100 is driven by a drive means (not shown) to rotate in the direction indicated by arrow S in FIG. 21. On the other hand, the polishing pad 200 is held by a platen 400 and driven by another drive means (not shown) to rotate in the direction indicated by arrow T in FIG. 21. As the object of polish 100 and the polishing pad 200 are made to abut each other under this condition, the contact surface of the object of polish 100 is polished.
During this operation, a polishing agent (slurry) is fed from a slurry supply means 500 to between the object of polish 100 and the polishing pad 200 that are held in touch with each other. Such a polishing agent typically contains fine particles (polishing particles) of SiO2 having a size of sub-microns to microns and dispersed in an alkaline aqueous solution. As slurry is supplied to the object of polish, the latter is finely polished. In FIG. 21, slurry is fed to between the object of polish 100 and the polishing pad 200 from the outside of the object of polish 100.
However, it is highly difficult to maintain the reproducibility of the polishing effect when polishing a plurality of objects continuously by means of a polishing apparatus having a configuration as described above. For example, the objects of polish can be polished to different extents and/or some of the objects of polishing can show unexpected scars on the surface. Such scars are mostly produced by particulate aggregates of fine dirt particles of external origins and/or those of polishing particles.
Additionally, the number of particulate aggregates increases with time. Conventionally, the slurry that is found to be containing particulate aggregates to a large extent is simply disposed as waste. Then, the operator is forced to frequently monitor the extent of the particulate aggregates to consequently raise the workload on the part of the operator.
Therefore, the object of the present invention is to provide a polishing method and a polishing apparatus that can supply slurry containing no large particles to the object of polish.
According to an aspect of the invention, the above object is achieved by providing a polishing apparatus of the type comprising:
an object-of-polish-holding means for holding an object of polish; and
a polishing head; and
adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means;
said polishing apparatus further comprising:
a container (or vessel) for containing said slurry;
an intake pipe for taking up said slurry from said container; and
a large-diameter-particle-screening means for screening off large diameter particles from the slurry leaving said intake pipe and being fed to said object of polish.
According to the invention, there is also provided a polishing method for supplying slurry from a container to an object of polish held by an object-of-polish-holding means and polishing said object of polish by means of a polishing head, said method comprising a step of:
supplying said slurry from said container to said object of polish by way of an intake pipe and screening off large diameter particles from the slurry leaving said intake pipe and being fed to said object of polish by a large-diameter-particle-screening means.
According to the invention, there is also provided a polishing apparatus of the type comprising:
an object-of-polish-holding means for holding an object of polish; and
a polishing head; and
adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means;
said polishing apparatus further comprising:
a container for containing said slurry;
an intake pipe for taking up said slurry from said container; and
a fractionizing means for fractionizing particulate aggregates contained in the slurry flowing through said intake pipe into fine particles.
According to the invention, there is also provided a polishing method for supplying slurry from a container to an object of polish held by an object-of-polish-holding means and polishing said object of polish by means of a polishing head, said method comprising a step of:
fractionizing particulate aggregates contained in the slurry taken up from a container and flowing in a given direction into fine particles by a fractionizing means.
According to the invention, there is also provided a polishing method for supplying slurry from a container to an object of polish held by an object-of-polish-holding means and polishing said object of polish by means of a polishing head, said method comprising steps of:
fractionizing particulate aggregates contained in the slurry flowing through a flow path running in a given direction into fine particles by a fractionizing means arranged at said flow path.
According to the invention, there is also provided a polishing apparatus of the type comprising:
an object-of-polish-holding means for holding an object of polish; and
a polishing head; and
adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means;
said polishing apparatus further comprising:
a first container for containing said slurry;
a fractionizing means for fractionizing particulate aggregates contained in the slurry contained in said first container into fine particles;
a transfer pipe for transferring said slurry from said first container to a second container;
a filter arranged in said transfer pipe for screening off particulate aggregates from the slurry passing through said transfer pipe; and
a feed pipe for feeding slurry from said second container to said object of polish.
According to the invention, there is also provided a polishing method for polishing an object of polish by causing the polishing surface of a polishing head to abut said object of polish, while supplying slurry to said object of polish held by an object-of-polish-holding means, said method comprising steps of:
fractionizing particulate aggregates contained in the slurry contained in a first container into fine particles;
screening off particulate aggregates from the slurry being transferred from said first container to a second container through a transfer pipe by means of a filter; and
feeding slurry from said second container to said object of polish by way of a feed pipe.
According to the invention, there is also provided a polishing apparatus of the type comprising:
an object-of-polish-holding means for holding an object of polish; and
a polishing head; and
adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means;
said polishing apparatus further comprising:
a hermetically sealable container for containing said slurry;
a gas supply means for supplying gas into said container; and
a feed pipe for feeding said said slurry to said object of polish.
According to the invention, there is also provided a polishing apparatus of the type comprising:
an object-of-polish-holding means for holding an object of polish; and
a polishing head; and
adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means;
said polishing apparatus further comprising:
a hermetically sealable first container for containing said slurry;
a gas supply means for supplying gas into said container; and
a transfer pipe for transferring said slurry from said first container to a second container; and
a feed pipe for feeding said slurry from said second container to said object of polish.
According to the invention, there is also provided a polishing method for polishing an object of polish by causing the polishing surface of a polishing head to abut said object of polish, while supplying slurry to said object of polish held by an object-of-polish-holding means, said method comprising a step of:
feeding slurry to said object of polish by way of a feed pipe by supplying gas into a hermetically sealable container containing said slurry.
According to the invention, there is also provided a polishing method for polishing an object of polish by causing the polishing surface of a polishing head to abut said object of polish, while supplying slurry to said object of polish held by an object-of-polish-holding means, said method comprising steps of:
transferring said slurry to a second container by way of a feed pipe by supplying gas into a hermetically sealable first container containing said slurry; and
feeding said slurry from said second container to said object of polish by way of a feed pipe.
Thus, according to the invention, it is now possible to prevent large diameter particles from being fed to the object of polish with slurry and thereby from forming unexpected scars on the surface of the object of polish by means of a polishing apparatus of the type comprising an object-of-polish-holding means for holding an object of polish and a polishing head and adapted to polish said object of polish by causing the polishing surface of said polishing head to abut said object of polish, while supplying slurry to said object of polish held by said object-of-polish-holding means because said polishing apparatus further comprises a large-diameter-particle-screening means.
Additionally, large diameter particles passing through the intake pipe can be fractionized by arranging a fractionizing means at the intake pipe as a large-diameter-particle-screening means.
Alternatively, large diameter particles passing through the intake pipe can be screened off by arranging a filter at the intake pipe as a large-diameter-particle-screening means.
Alternatively, large diameter particles can be prevented from entering the container from the outside by using a hermetically sealable container as a large-diameter-particle-screening means.
According to the invention, it is now possible to fractionize almost all the particulate aggregates contained in the slurry flowing through a flow path running in a given direction into fine particles by a fractionizing means arranged along the flow path.
Almost all the slurry contained in the container is taken up into the intake pipe and passes therethrough. Additionally, almost all the particulate aggregates contained in the slurry flowing through the intake pipe can be fractionized by a fractionizing means arranged at the intake pipe before the slurry is fed to the object of polish.
Thus, since the slurry fed to the object of polish is free from particulate aggregates, it is now possible to prevent unexpected scars from being formed on the surface of the object of polish.
According to the invention, almost all the particulate aggregates contained in the slurry in the first container can be fractionzed into fine particles. Unfractionized large diameter particles can be screened off by means of a filter. The fine particles contained in the slurry in the second container can be made to grow to show a uniform size which is preferable for polishing. Thus, slurry that is free from large particles and containing only particles of desired size can be fed to the object of polish for polishing.
According to the invention, it is possible to transfer the slurry contained in a hermetically sealable container by way of a feed pipe without being exposed to the atmosphere by supplying compressed gas into the container so that large diameter particles contained in the atmosphere can be effectively prevented from entering the slurry contained in the container.
Additionally, the slurry contained in the container is prevented from evaporating because the container is hermetically sealable.
As a result, slurry containing stably dispersed particles can be fed to the object of polish for a prolonged period of time.